Apparatuses for actuating a switch in response to elevational movement of at least a portion of a seat assembly of a vehicle such as a lift truck are well known in the art. Examples of such systems are shown in U.S. Pat. No. 2,708,005 to Gazzo issued May 10, 1955, U.S. Pat. No. 3,437,993 to Recio et al issued Apr. 8, 1969, U.S. Pat. No. 3,500,946 to Boyajian issued Mar. 17, 1970; U.S. Pat. No. 3,703,618 to Lewis issued Nov. 21, 1972; U.S. Pat. No. 3,704,352 to Fontaine issued Nov. 28, 1972, U.S. Pat. No. 4,075,443 to Fatur issued Feb. 21, 1978, and German Pat. No. 1,048,784 issued Jan. 15, 1959.
Such apparatuses are often disposed between the seat assembly and the switch for actuating the switch in response to movement of the seat assembly toward the switch due to the weight of a vehicle operator being seated thereon and for deactivating the switch in response to movement of the seat assembly away from the switch due to the weight of the vehicle operator being removed therefrom.
Typically such switches are operatively connected to a vehicle system for establishing an on or off condition of the system, as determined by an occupied or unoccupied vehicle seat assembly, and permitting or preventing travel of the vehicle.
It has been found that during operation of the vehicle over rought terrain prior switch actuating apparatuses are often too sensitive to seat assembly movement which causes cyclical and undesirable actuation of the switch between the actuated and unactuated positions which results in turning on and off the vehicle system.
Such prior actuating apparatuses do not have provisions for limiting the maximum amount of actuating force applied to the switch. Since the weight of the operator under dynamic conditions applies a variable force to the seat assembly of a substantial magnitude and the force applied to the switch is proportional to the force on the seat, a condition may be developed when the switch actuating force is beyond the structural limits of the switch. This excessive force can cause premature failure of the switch which will result in down time of the vehicle.
Often the switch is mounted on the seat assembly for elevational movement with or in response to elevational movement of the seat assembly. When this movement is appreciable, substantial flexing of electrical wires connecting the switch to the vehicle system is observed. This flexing frequently causes breakage of the wires which causes vehicle downtime. Also, since the switch is mounted on the seat assembly removal of the seat assembly from the vehicle or movement of the seat assembly for operator comfort adjustment in a horizontal direction relative to a seat support surface causes substantial flexing, stretching and bending of the wires. Also, removal of the seat assembly frequently requires disconnection or removal of the switch. In addition, such systems do not include a provision wherein ease of adjustment of the actuating apparatus can be made for establishing the minimum weight on the seat at which switch actuation is achieved.
The present invention is directed to overcoming one or more of the problems as set forth above.